Wheel mounting



3 Sheets-Sheet 2 D FIRTH WHEEL MOUNTING Oct. 10,` 1950 Flled Nov 21 1947D. FlRTH WHEEL MOUNTING ocr. 1o, 195o 3 Sheets-Sheet 5 Filed Nov. 2l,1947 A Q @i .N Q s ww m mw uw. Nw E @N W. Q, NN`\\ @N mx @w G @Nn Q, li.: ,mm @Kw Patented ct. 10, 195,0 o

WHEEL MOUNTNG David Firth, South Bend, Ind., assigner to DodgeManufacturing Corporation, Mishawaka, Ind., a corporation f IndianaApplication November 21, 1947, Serial No. '787,335

1 Claim.

l This invention relates to wheel mountings for use under conditionsrequiring axial adjustability Fig. 4` is a section taken half on theline A-A and half on the line B-B of Fig. 3, looking in of the mountedwheels. The invention resides in the directions of the arrows.

a species of a broader invention described and Fig. 5 is a section takenon the line C-C of claimed in my copending application Serial No, 5 Fig.3, looking in the direction of the arrows. '787,336 for Wheel Mountings,filed concurrently Fig. 6 is a section taken on the line A-A ofherewith, now Patent No. 2,519,958. Fig. 3, showing the bushingdewedged.

In said copending application, I disclose a In the drawings, the drivingor traction wheels wheel mounted on a screw-threaded axle through of afarm tractor are designated by the numeral the medium 0f a,correspondingly internally 10 i. TheSe Wheels halle taper-boled hllbS 2in screw-threaded tapered split contractible bushwhich are fittedresilient tapered bushings 3 split ing tting a tapered bore in the wheelhub and longitudinally aS indicated at il t0 permit conscrewa'ble onSaid .axle when the bushing is in traction thereof. The wheels showncomprise anunoontraoteo state. The mounting structure inrlular diSGS 5equipped with rims 6 Carrying the clndes Screw equipment for forcing thennb `on l5 wheel tires l, said discs 5 being affixed by screws thebushing to contract it tight on the axle and 8 t0 radial flanges 9 onthe wheel hubs 2. for forcing the hub off the bushing to release it, Thedriving aXle shafts for said wheels are these operations being referredto as the wedgdeSgIlated by the numeral l0. These shafts are ing anddewedging of the bushing The Screw mounted each in bearings Il and l2 inthe drivequipment shown for this purpose in such cor i0 ing aXi Shafthousing I3, WhCii iS SUDDOTted by pending application is of the typedisclosed in said shafts from the wheels. The bearings ll pai-,eng toFirth, No 2,402,743I of June 25, 194@ and l2 for each shaft are arrangedto sustain A wheel mounting embodying the present in- Opposite endthrusts, whereby the shafts are held vencion is characterized by Screwequipment from axial displacement. Fixed on these alined comprising aSet of screws in threaded engage zo shafts are gears hl by which theshafts are sepament with only the wheel hub, and thrust-transfatelidriven fiOm the traCtOr motor through miti-,ing plates connected by SaidScrews and suitable diierential gearing (not shown), to perabutting theopposite ends of ine bushing, the mit the wheels to be driven atdifferent angular construction being such that the bushing can be Speedsas the taCtOl makes a turn 01 travels. wedged by rotating the screws inone direction :l0 Otherwise than in a Stlaght lille, thus avoiding anddewedged by rotating the screws in the opundue Wear 0n the tirespostedirection The shafts It are formed with extended screw The inventionfinds a eld of useful application axles i5 on which the wheel hubs aremounted in farm tractors, the driving or traction wheels through themedium 0f their' tapered split conof which need to be axially adjustedfrom time to acume bushings 3, the latter having i tapped time to suitthe spacing of rows of plants bel-,Ween bores forming internal screwthreads matchingY which the Wheels are to be run. Adjustment of andinterengaged with those of said screw axles. suchwheels often involvesvery severelabor, but The .ntefelgagng threads 0f Said axles and isr-endered relatively easy vby the use of wheel bushmgs are designatedI'eSDeCtiVely by the numountings of the type to which tno invention lomerels li and il- An appropriate working clearrelai-,es l ance existsbetween these threads when the bush- An illustrative embodiment of theinvention in mgs are m uncontmcted State- In Fig. 4, the one practicableform is shown ln the accom tapered exterior surface of the bushingtherein 1ianying drawings, wherein: shown is indicated by the obliquedotted lines 3a.

l Fig. l is a longitudinal Vertical Section of a YEach wheel hub hasassociated screw equipi-,raoi-,or driving Wheel and Shaft assemblyhaving ment whereby, when the wheel is raised from the wheel mountingsembodying the invention, the ground by jiilg U-U the adjallt'ciid of thesection being taken through the housing for the dni/ing @X12 Shafthousing, the Wheel can be driving axle Shafts and Said Shafts beingShown forcibly moved relative to the bushing to compress in elevation.it by the hub tight on` its screwl axle, thereby Fig. 2 is a detail Viewof interengaging axle and Wedgilg the bushing, and Cari be I'eVerSelymOi/'ed bushing threads of a type best adapted for the to dewedge 0rrelease the bushing so as to permit purpose of the invention. it toresume its uncontracted state. The screw Fig. 3 is an end elevation ofthe central portion equipment provided in the illustrative construcofone of the driving or traction wheels. 55. tion comprises a single setof screws I8 operable in one direction for wedging and reverselyoperable for dewedging.

As shown in Figs. 3 to 6, the holes for the screws I8 are formed partlyby hub grooves I9 having tapped walls forming female screw threadsengaged by the threads of said screws, said female threads beingmutilated or cut by the tapered hub bore, and partly by smooth-walledbushing grooves 2l confronting said hub grooves and of appropriatecurvature for cooperation therewith to provide screw-holes in which saidscrews can be operatively tted. Thus the screws are in threadedengagement only with the hub. The bushing 3 projects at both ends beyondthe ends of the hub 2. The screws I8 consist of cap screws the heads 22of which bear indirectly against the large end of the bushing through aninterposed thrust-transmitting annular plate 23 abutting the bushing,there being clearance between said plate and adjacent end of the hubwhen the bushing is wedged, as shown in Fig. 4. It will be understoodthat the shanks of the screws I8 pass loosely through holes in saidplate in registration with the screw-holes aforesaid. Abutting the smallend of the bushing is a similar annular plate 2d. The screws I8 extendloosely through holes in said plate 24 and have aiixed thereon nuts 25which are screwed on said screws and pinned or riveted thereto, saidnuts 25 being spaced from said plate 24 when the bushing is wedged. Towedge the bushing, the screws I8 are screwed up to bring the screw heads22 against the plate 23 and are then tightened to draw the wheel hubforwardly on the bushing. To dewedge, the screws are operated reverselyor in the unscrewing direction to bring the nuts 25 against the plate 24and are then tightened by further operation in the unscrewing directionto draw the bushing backward suciently to release the bushing, therebeing clearance between the plate 24 and hub 2 when the bushing isdewedged, as appears from Fig. 6.

Utilization for the wedging and dewedging functions of screw equipmentof the type disclosed affords the further advantage that the screwsserve as keying means, whereby the bushing when loose in the hub can bescrewed on the wheel axle by rotating the wheel.

Referring further to Figs. 3 to 6, the tightness with, which the bushing3 can be wedged depends upon its taper. It is desirable for effectivewedging that the angle of taper of the bushing i. e. the included anglebetween diametrically opposite longitudinal contour lines thereof, benot greater than and preferably substantially less than thirteendegrees. On the other hand, an extremely slight taper of the bushingmight result in such tight wedging thereof as to render dewedging undulydiicult. An angle of taper of from about six to about nine degrees ispreferred. This will allow such tight wedging of the bushing as toobtain a press tight lt thereof in the hub, without making it undulydicult to dewedge the bushing.

An appropriately tapered bushing tightly wedged grips the hub with sucha powerful hold as to affordv a driving connection for transmission ofhigh torque. Keying of the hub to the bushing is believed to beunnecessary, except to enable the bushing when loose in the hub to bescrewed on the screw axle I5 by rotating the wheel. In any event, thescrews I8 or at least one of them afford a sufficient driving keyconnection between the hub and bushing, if it be needed.

Reference will now be made to the threading of the screw axles I5 andcorresponding internal threading of the hub bushings 3. Easy axialadjustment of the driving wheel is not dependent upon the form of theinterengaging screw threads of said axles and bushings, since,regardless of the type of screw threads utilized, the bushings may bekeyed to the screw axles as hereinafter explained. It is desirablehowever to minimize or obviate keying requirements, or to minimizetorque reactions on such keying connections between the bushings andaxles as may be employed. It is accordingly desirable to form said axlesand bushings with screw threads of appropriate form and proportions forinterwedging of their convolutions, so that the bushings when tightlywedged will grip the screw axles with such powerful holding eiect as toafford driving connections capable of transmitting high torque.

In the illustrative structure, the screw axle and hub bushing for eachwheel are formed, as shown in Figs. 3 to 6, with large interengagingscrew threads I6 and II of the type known in the screw industry as Acmethreads. These are broad topped threads having sloping sides of steepslant, and are desirable for their sturdiness as Well as for the muchsteeper slant of their sides than those of ordinary V-type threads. Asshown in Fig. 2, said screw threads I5 and I'I are proportioned forinterwedging. rThe two threads are of the same cross-sectional form anddimensions, and of the same radial dimensions as the spiral grooveswhich are cut to form the threads; but their transverse dimensions, in aplane in which the hub axis lies, are slightly greater than thecorresponding dimensions of said grooves. Hence when the bushing 3 iscontracted tight on the screw axle, the convolutions of each thread aretightly wedged between the convolutions of the other, leaving clearancebetween the tops of the threads and bottoms of said grooves as indicatedat 26 in Fig. 2.

Screw threads of the Acme type can be interwedged much more tightly thanordinary threads of V-shaped cross-section. In the case of o. standardV-thread, the included angle between adjacent convolutions thereof issixty degrees, whereas in the case of a standard Acme thread theincluded angle between adjacent convolutions thereof is only twenty-ninedegrees. Fur ther advantage with respect to tight interwedging may begained by utilizing Acme threads having sides of still steeper slant. Aslant such that the included angle aforesaid is only twenty degrees visconsidered preferable. Fig. 2 may be considered as representing tightlyinterwedged Acme threads having sides of such preferred slant.

It will be understood that by the tight interwedging of the screwthreads of the screw axles and bushings, driving connections areestablished independently of or supplementing such connections as may beprovided by keying the bushings to the axles; that the connections soobtained would be of fairly high torque-transmitting capacity if thethreads were V-threads having their tops truncated to permitinterwedging; that the connections obtainable by the tight interwedging0f standard Acme threads are of very high torque-transmitting capacity,and that connections of still higher torque-transmitting capacity areobtainable by use of Acme threads having sides of the preferred slantdescribed with reference to Fig. 2. With the use of Acme threads, andespecially those having sides of such preferred `ment with those of thescrew axle.

slant, it is thought keying of the bushings to the screw axles may beunnecessary.

If however it be necessary or deemed advisable, the driving connectionsestablished between the screw axles and bushings by the inter- Wedgingof their screw threads may be supplemented by keying. For example, thehub bushing of each wheel may be keyed to the screw axle, as shown inFigs. 3 and 5, by a removable key 2 fitting slidably in a keyway orgroove 28 in and extending the full length of the screw axle and in amating keyway or groove 29 in the bushing,

in which case, before wedging the bushing, the wheel need be given onlya half turn or less to register said grooves. The key may be insertedbefore wedging the bushing if the proportions of the key relative to thedepth of the grooves is such as to provide clearance between the key andthe bottoms or grounds of the grooves when the bushing is wedged, so asto avoid any interference with contraction and tight wedging of thebushing. A straight key as shown is preferred, though in lieu thereof atapered key could be employed, to be driven after wedging of the bushingbetween the seat therefor provided by the groove 28 in the `axle and aseat provided by a bushing groove of gradually diminishing depth. Thekey, whether straight or tapered should be removable. The key shown hasa head 3|] which when the key is in place is spaced suciently from theplate 23 to permit driving a wedge between said plate and head forforcing out the key in case it should become stuck.

Upon dewedging the bushing 3 of either wheel hub, the bushing willexpand to uncontracted state if its spring force is sufficient towithdraw its thread convolutions from frictional engage- Should thebushing when dewedged fail to release itself from gripping engagementwith the screw axle, due to tight interwedging of said threads, or incase the bushing after long service in wedged condition should havebecome set in contracted state, its

release from theA shaft can be effected by forcing an appropriatespreading tool into the bushing split. To facilitate spreading orexpanding it under such conditions, each bushing 3, as shown in Figs. 3and 6, is provided at the opposite ends of its longitudinal slot 4 withlongitudinal grooves or recesses 3| in the confronting walls of saidslot, in the form of segments of conical screwholes. When the bushing iscontracted, the opposing recesses 3l form approximately conical screwholes intersected longitudinally by the slot ll, as shown in Fig. 3, inwhich holes asuitable tool, e. g., a piece of iron pipe having athreaded end, can be worked to spread or expand the bushing.

To change the distance between the driving wheels of the illustrativestructure, each wheel in turn is jacked up and released from drivingconnection with its axle by withdrawing the key 2l', dewedging thebushing 3 and expanding it by aid of a spreading tool if necessary. Thereleased wheel is then adjusted in or out as desired by rotating thewheel in the proper direction for adjustment, requiring onlycomparatively slight effort. The adjusted wheel is then given suchslight turn as may be required for registering the keyways 28 and 29,whereupon the wheel is again secured in driving connection with the axleby reinserting the key and wedging the bushing by operation of thescrews I8.

lt is within contemplation to form the screw` axles l5 and hub bushings3 with interengaging doubleor triple threads or other pluralities ofscrew threads of relatively large pitch, each thread of each bushingfitting and wedgeable between two threads of the corresponding screwaxle. The effect would be to increase the resistance to turning of thewheels on the screw axles when the bushings are uncontracted, and henceto increase the torque-transmitting capacity of the friction-gripconnections between the axles and bushings. In the appended claim,interengaging threads will be understood to include such interengagingpluralities of threads.

I claim: y

A wheel mounting comprising a taper-bored hub, a screw-threaded axle, atapered split contractible bushing tting the bore of said hub and havingan internal screw thread matching and interengaged with the thread ofsaid axle, the bushing when uncontracted being screwable on and ofi fromsaid axle by rotating the hubsaid hub and bushing having confrontinggrooves forming screw holes having threaded walls only in the hub,screws in said holes the threads of which engage the threads of saidthreaded walls, said bushing being slightly longer than and protrudingfrom the ends of the hub, thrust-transmitting plates abutting the endsof the bushing and having holes through which said screws extendloosely, said screws having heads to bear against the plate abutting thecorresponding end of V4said bushing, the threaded Shanks of said screwsextending through the other plate and having nuts fixed thereon, wherebythe screws can be operated in opposite directions for forcing the hub onthe bushing to contract it and off from the bushing to release it.

DAVID FIRTH.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,324,681 Dekker July 20, 1943 .Y2,402,743 Firth June 25, 1946

